An engine may include both port and direct fuel injectors to improve engine operation. Port fuel injectors may solely inject fuel to engine cylinders at low engine speeds and loads where fuel vaporization is good and the possibility of engine knock is low. Direct fuel injectors may inject fuel solely to the engine at higher engine loads to reduce the possibility of engine knock and increase engine output power.
Engine cylinders may be deactivated via deactivating fuel flow to the cylinders during low engine load conditions to conserve fuel. Combustion ceases in the deactivated cylinders as fuel flow ceases to the deactivated cylinders. Nevertheless, the engine may continue to rotate even after fuel flow to the cylinders is deactivated via the vehicle's kinetic energy being imparted to the engine via the vehicle wheels and transmission.
If engine cylinders are reactivated using fuel injectors according to an engine fuel schedule map that is indexed by engine speed and torque, it may be possible that a cylinder reactivation delay occurs because port injection of fuel into a cylinder requires that end of fuel injection occurs before intake valve closing of the cylinder cycle in which the fuel is to be inducted. A delay in cylinder reactivation may delay engine torque production and decrease vehicle drivability.
The inventors herein have recognized the above-mentioned disadvantages and have developed an engine operating method, comprising: directly injecting fuel to a cylinder for a first combustion event in the cylinder after the cylinder is deactivated via ceasing combustion in the cylinder, the engine continuing to rotate without stopping an entire time while the cylinder is deactivated; and port injecting fuel to the cylinder a first time after the cylinder is deactivated for a second combustion event in the cylinder after the cylinder is deactivated.
By reactivating engine cylinders via direct injection even though the cylinders would receive port injected fuel during similar operating conditions, it may be possible provide the technical result of quicker cylinder reactivation. In particular, since direct fuel injectors may inject fuel later in a cylinder cycle, such as during a compression stroke of the cylinder, it may be possible to start combustion in a cylinder where the intake valves of the cylinder are closed after a request to reactivate engine cylinders. Consequently, production of engine torque may commence in a shorter period of time after a request to reactivate engine cylinders.
The present description may provide several advantages. Specifically, the approach may reduce hasten cylinder reactivation. In addition, the approach may improve engine air-fuel control. Further, the approach may improve vehicle drivability.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.